I'm having a problem with power saving on my monitor and would really appreciate any advice that I can get.

I have a Dell T3500 workstation with a Nvidia Quadro 580FX video card. I'm using a display port connection to a Dell flatscreen monitor. It all works perfectly, or at least it used to.

Back when the 290.10 nvidia drivers were current (and before then), the computer was set to have the screen saver come on after a few minutes and then the monitor would power down after 15 minutes. It worked perfectly. Then came the 295 series drivers and suddenly my monitor lost the ability to power down. Instead the screen saver would just freeze in place. If I hit the keyboard or jiggled the mouse, the screen would refresh to the unlock screen. I manually reverted to the 290.10 driver and all was fine.

However, in June when xorg-server 112.2 came out, it wouldn't work with the 290.10 driver and I was forced to update the nvidia driver. Now I'm back to having a stopped screen saver on my screen which isn't doing anything good for my power consumption at night.

I'm currently using nvidia-drivers 304.37, xorg-server 112.2, and kde 4.8.3.

Also, one interesting thing, if I say "xset dpms force off" the screen blanks for a moment and then my kde screensaver appears. I wonder if this is saying that it's a kde problem.

Open your /var/log/Xorg.0.log and check for any mention of dpms.
Gerard._________________To install Gentoo I use sysrescuecd.Based on Gentoo,has firefox to browse Gentoo docs and mc to browse (and edit) files.
The same disk can be used for 32 and 64 bit installs.
You can follow the Handbook verbatim.
http://www.sysresccd.org/Download

That's what I have too and dpms works fine with nvidia-295.71.
Something in your desktop?
Gerard._________________To install Gentoo I use sysrescuecd.Based on Gentoo,has firefox to browse Gentoo docs and mc to browse (and edit) files.
The same disk can be used for 32 and 64 bit installs.
You can follow the Handbook verbatim.
http://www.sysresccd.org/Download

I finally got around to trying to fix this problem, and I feel like an idiot.

So the configuration again is a nvidia Quadro Fx 580 card driving a 27" dell monitor at 2560x1440 pixels. Most recent stable nvidia drivers, most recent xorg, most recent kde, etc. I have another nearly identical computer in the other room and it puts the screen to sleep without a problem, but this one doesn't.

After ~6 months of screwing with my xorg.conf, I ran across a forum post saying that they were having problems with dpms using a displayport connection. I realize that that's the only difference between the other machine and this one. The computer that works was using a dvi connection, the one that wasn't was using displayport.

So I swapped out the displayport cable for a dual-link dvi cable and everything now works exactly the way it's supposed to.

So the lesson is that you should beware of displayport connections.

The thing I really don't understand though is that it did work long ago with older drivers and an older version of X. Somewhere along the way in the stream of updates, something got broken.